A new potentiometric sensor for the rapid determination of Hg2+ based on modified carbon paste electrode consisting of room temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6), multi-walled carbon nanotubes (MWCNTs), alumina nanoparticles and a synthetic macrocyclic diamide ‘7,10,13-triaza-1-thia-4,16-dioxa-6,14-dioxo-2,3;17,18-dinaphtho-cyclooctadecane’ as an efficient ionophore was constructed. Prepared composite is an ideal paste because it has low drift of potential, high selectivity and fast response time (10 s), which leads to a more stable potential signal. The morphology and properties of electrodes surface were characterised by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. A linear dynamic range of 2.01–2.01 × 107 µg L−1 with detection limit of 1.40 µg L−1 Hg2+ was obtained at pH range of 2.5 to 4.5. The prepared modified electrode shows several advantages such as simple preparation method, high stability of the composite paste, high sensitivity, long-term life time (at least 13 weeks) and remarkable potentiometric reproducibility. The modified electrode was successfully applied for the accurate determination of trace amounts of Hg 2+ in environmental samples.
